LG G7(thin) help removing sprints message that contiounsly pops up

Addicted Lv. 3

I have a LG G7 that is thru sprint but unfortunately the company put a continous pop up reminder that requested the phone back due to the account having money owed still. The message goes away at least when I click out of the window but never fails to pop up when I am trying to do something on the phone and it gets pretty annoying. Does anyone know if there is a way to get the phone unattached to the sprint account? I'm not sure if it's possible but I had a friend tell me I can go and clone the phone and it would do the trick but I want to make sure so I don't waste my time.